Cryogenic fluid piping systems, for example, for transport of liquified natural gas (LNG) or other cryogenic fluids, typically, employ vacuum-jacketed male and female bayonet connectors therein.
U.S. Pat. No. 3,885,595, issued May 27, 1975, shows a conduit for cryogenic fluid transport. Each conduit section has a male and a female end such that the conduit section can be laid end to end with similar conduit sections to form a continuous conduit. Each conduit section has an inner and an outer pipe. The space between the inner and outer pipe is filled with insulation. Both the male end and female end are frusto-conical in shape and telescoped together in use. A thermal motion compensator, i.e., a metal bellows, is secured about the female end of the inner pipe. In the assembled state, the outer pipes of adjacent conduit sections are welded to each other. In the operating state, pressure from the cryogenic fluid flowing inside the inner pipe acts upon the outside of the thermal motion compensator and is contained from the environment by the outer pipe welds. A liquid seal is provided between the male and female ends of the inner pipe.
German Patent No. 315487, issued Jul. 25, 1931, shows an expansion-compensating conduit connection. A male end of a first conduit section is inserted into a female end of a second conduit section. An expansion compensator is located on the male end of the first conduit section.
U.S. Pat. No. 4,515,397, issued May 7, 1985, shows a vacuum-insulated conduit. The conduit comprises an inside pipe and an outside pipe. A plate having a radially solid portion connects the end of the outer pipe to one end of a bellows, which is located around a portion of the inner pipe that extends beyond the end of the outer pipe. The opposite end of the bellows is connected to the outer circumference of the inner pipe. The space between the inside and outside pipe is evacuated to form a vacuum. Other U.S. patents relative to cryogenic systems include U.S. Pat. No. 4,011,732, issued Mar. 15, 1977, and U.S. Pat. No. 4,107,946, issued Aug. 22, 1978.
It is desirable to provide a new, improved, vacuum-jacketed, male-female bayonet connector particularly useful in cryogenic fluid piping systems, such as LNG systems, and which connectors allow for stress-free thermal expansion and contraction and eliminate or reduce the need for expansion loops in the system.
The invention relates to a male-female bayonet or pipe spool connector with a male bayonet with an expansion bellows and a cryogenic fluid piping system employing the connector.
The invention comprises and is directed to a bellows and male bayonet connection for connecting vacuum-jacketed pipe spool sections to one another. The connection allows stress-free thermal expansion and contraction of the inner pipe within each spool, thus, eliminating or reducing the need for expansion loops. Within an outer pipe is an inner pipe. The inner pipe carries cryogenic fluid at a certain pressure and temperature. The space between the outer pipe and the inner pipe is evacuated to form an insulating vacuum jacket around the inner pipe. The male end of the spool comprises a male bayonet portion and expansion peripheral bellows secured about the exterior of the male bayonet at the open end. The male bayonet portion is attached to a first annular seal between the male bayonet portion and the outer pipe at one end and to the bellows at the other open end. The opposing end of the bellows is attached to a male end of the inner pipe. The spaces between the male bayonet portion and the inner pipe, between the bellows and the inner pipe and between the outer pipe and the inner pipe, communicate with one another and are at the same vacuum pressure.
The female end of the spool comprises a female bayonet portion that is attached to a female end of the inner pipe. The opposing end of the female bayonet portion is attached to a second annular seal between the female bayonet portion and the outer pipe. The spaces between the female bayonet portion and the outer pipe, and between the outer pipe and the inner pipe, communicate with one another and are at the same vacuum pressure. The male and female spool ends connect together by a means to connect, such as a bolted flange connection, a clamped connection, or a welded connection. When a rise or fall in temperature causes the inner pipe to lengthen or shorten, the male end of the inner pipe moves and extends or compresses the surrounding secured bellows. The female end of the inner pipe is fixed to and does not move in relation to the female bayonet portion. The bayonet connection results in a nearly uninterrupted, smooth interior wall of the inner pipe that is conductive to smooth, non-turbulent, cryogenic fluid flow.
The invention comprises a cryogenic fluid piping system with a plurality of two or more coupled first and second pipe spools, the first pipe spool having an outer pipe and a concentric inner pipe to carry cryogenic fluid, the outer pipe and inner pipe forming a vacuum-insulated connection, and a male bayonet at the one end of the first pipe spool having an external, male sealing surface, and having a first open end and other end, and an expansion-contraction peripheral bellows longitudinally about the external surface of the male bayonet adjacent the first open end, and a means to secure the one end of the bellows about the external surface to the first open end of the male bayonet.
The invention also comprises a second pipe spool having an outer pipe and a concentric inner pipe to couple with the first pipe spool to carry cryogenic fluid in the coupled inner pipe and to form a coupled, vacuum-insulated connection, the female bayonet having an internal, female sealing surface and a first open end and other, end arranged and constructed to form a telescoped, zero tolerance, cryogenic vapor seal between the external surface of the male bayonet and the internal surface of the female bayonet for the stress movement of the bellows in the coupled use position; and a means to connect the opposing ends of the outer pipe of the first pipe spool and the second pipe spool.
The invention will be described for the purpose of illustration only in connection with certain illustrated embodiments; however, it is recognized that various changes, modifications, additions, and improvements may be made by those persons skilled in the art of the invention, as described and disclosed, without departing from the spirit and scope of the invention.